Functional regenerated cellulose fibers

ABSTRACT

Fabrics comprising regenerated cellulose fibers and a nanoparticle dispersed throughout the fabric are disclosed herein. The regenerated cellulose fibers can be derived from a biomass such as a fibrous cellulose, wood pulp, cotton, paper, bast fiber, bagasse, or a combination thereof. The nanoparticle included in the fabric can be chosen to confer a desirable property, such as a thermal insulating property, to the fabric. Methods of making the fabrics comprising the regenerated cellulose fibers and nanoparticle are also provided. The method can include (a) at least partially dissolving a cellulose substrate in a medium comprising one or more ionic liquids; and dissolving or suspending a nanoparticle in the medium; (b) recovering a solid nanoparticle-modified regenerated cellulose material comprising the cellulose substrate and the nanoparticle; and (c) processing the solid nanoparticle-modified regenerated cellulose material to form the fabric.

FIELD OF THE DISCLOSURE

This disclosure relates generally to regenerated cellulose fibers, more particularly, to regenerated cellulose fibers comprising a functional material.

BACKGROUND OF THE DISCLOSURE

Building heating, ventilation, and air conditioning (HVAC) account for 13% of energy consumption in the United States. Nevertheless, up to 80% of the occupants are dissatisfied with the thermal environment, even though buildings meet thermal comfort criteria as determined by the ASHRAE Standard 55 and ISO Standard 7730. Physiological parameters such as sex, age, body composition, and metabolic rate can have a great effect on an individual's perception of the thermal environment. A study among young Europeans indicated that the preferred ambient temperature might vary as much as 10° C. between individuals. However, it is not yet clear how an individual's thermal comfort zone (TCZ) relates to the physiological thermo-neutral zone (TNZ).

Furthermore, the Department of Energy seeks to expand the setpoint on HVAC energy consumption from a baseline of 70.5-75° F. to 66-79° F. In particular, studies have shown, for example in the city of Phoenix, lowering the setpoint in the winter months to 66° F. results in an annual savings of ˜14% while raising the setpoint in summer months to 79° F. results in an annual savings of ˜20%. Consequently, a setpoint of 66-79° F. would save a total of ˜34% annually versus the comparative baseline building. In this regard, there is a need to develop Localized Thermal Management Systems (LTMS) to modify the local thermal envelope around the human body rather than the building.

A raised question for apparel manufacturers is if they could bring a purely passive thermal solution for their suiting products (typically suit and shirt for men and blazer and blouse for women), that is, capability of preventing 18 W heat loss due to the 4° F. setpoint decrease in winter, and of removing an extra heat of 23 W due to the 4° F. setpoint increase in summer.

Industrial attempts to produce thermal regulating fibers have been made in synthetic fiber manufacture, by use of specific inorganic particles as functional fillers added into polymers during fiber spinning. For example, nylon 6 fibers comprising 2% of α-type Al₂O₃ (AKP-30, APS 400 nm) is reported to have a thermal conductivity of 0.024 W/mK (Unitika Ltd., 1995).

Another example is polyester fibers comprising 90% polyester, 6% a-type Al₂O₃, and 4% ZrC which is reported to have a thermal conductivity as high as 2900 W/mK (Unitika Ltd., 1996), compared to regular polyester fiber (0.14 W/mK). Although the technologies for fabrication of these synthetic thermal regulating fibers have been reported for about 20 years, none of these fibers are used in today's fashion apparel products. There remains a need for clothing articles having thermal conductive properties. The compositions, systems, and methods described herein address these and other needs.

SUMMARY

Fabrics comprising regenerated cellulose fibers and a nanoparticle (e.g., a plurality of nanoparticles) dispersed throughout the fabric are disclosed herein. The regenerated cellulose fibers can be derived from a biomass such as a fibrous cellulose, wood pulp, cotton, paper, bast fiber, bagasse, or a combination thereof.

The nanoparticle included in the fabric can be chosen to confer a desirable property to the fabric. In some embodiments, the nanoparticle can be selected from a thermally conductive or insulating material, an electrically conductive material, an electromagnetic wave absorption or shielding material, a hydrophobic material, a fire retardant or suppressant, a water repellent material, a water absorbent material, a soil repellent material, a reflective material, an anti-microbial agent, a sunblock agent, a dye, a pigment, a fragrance, an insect repellent, a fabric softener, a UV-protective material, an oxidation resistant material, or a combination thereof. In some embodiments, the nanoparticle can include a thermal insulating material.

Examples of thermal insulating nanoparticles include far infrared radiation ceramics. In some embodiments, the fabric can include a nanoparticle comprising aluminum, iron, silver, cerium, zinc, gold, copper, cobalt, nickel, platinum, manganese, rhodium, ruthenium, palladium, titanium, vanadium, chromium, molybdenum, cadmium, mercury, calcium, zirconium, iridium, silicon, an oxide thereof, zeolite, graphite, a carbon nanotube, or a combination thereof. For example, the nanoparticle can comprise alumina, silica, titanium oxide, tin oxide, iron oxide, cesium oxide, zinc oxide, graphite, a carbon nanotube, or a combination thereof. The nanoparticle can be reactive or unreactive with the regenerated cellulose fibers. In some examples, the nanoparticle can include a silicon oxide nanoparticle, a silver nanoparticle, a cerium oxide nanoparticle, a zinc oxide nanoparticle, a poly(vinyl) alcohol nanoparticle, or a combination thereof.

The nanoparticle can be present in an amount of from 0.01% to 10% by weight, based on the total weight of the fabric.

Methods of making the fabrics comprising the regenerated cellulose fibers and nanoparticle are also provided. The method can include (a) at least partially dissolving a cellulose substrate in a medium comprising one or more ionic liquids; and dissolving or suspending a nanoparticle in the medium. The one or more ionic liquids can have a cation portion derived from an imidazole, a pyrazole, a thiazole, an isothiazole, an azathiozole, an oxothiazole, an oxazine, an oxazoline, an oxazaborole, a dithiozole, a triazole, a selenozole, an oxaphosphole, a pyrrole, a borole, a furan, a thiophen, a phosphole, a pentazole, an indole, an indoline, an oxazole, an isoxazole, an isotriazole, a tetrazole, a benzofuran, a dibenzofuran, a benzothiophen, a dibenzothiophen, a thiadiazole, pyridine, a pyrimidine, a pyrazine, a pyridazine, a piperazine, a piperidine, a morpholone, a pyran, an annoline, a phthalazine, a quinazoline, a quinoxaline, a quinoline, a pyrrolidine, an isoquinoline, or a combination thereof. The one or more ionic liquids can have an anionic portion selected from a halogen, a pseudo-halogen, BX⁴⁻ wherein X is halogen, PF⁶⁻, AsF⁶⁻, SbF⁶⁻, NO²⁻, NO³⁻, SO₄ ²⁻, BR₄ ⁻, phosphates, phosphites, polyoxometallates, carboxylates, substituted carboxylates, triflates, carboranes, substituted carboranes, metallocarboranes, and substituted metallocarboranes; wherein R is selected from hydrogen, alkyl, substituted alkyl, cycloalkyl, substituted cycloalkyl, heteroalkyl, hetero cycloalkyl, substituted heterocycloalkyl, aryl, substituted aryl, heteroaryl, substituted heteroaryl, alkoxy, aryloxy, acyl, silyl, boryl, phosphino, amino, thio, seleno, or a combination thereof.

In some embodiments, the one or more ionic liquids can be selected from 1-C₂ alkyl-3-methyl-imidazolium chloride, 1-C₃ alkyl-3-methyl-imidazolium chloride, 1-C₄ alkyl-3-methylimidazolium chloride, 1-C₆ alkyl-3-methyl-imidazolium chloride, 1-C₈ alkyl-3-methyl-imidazolium chloride, 1-C₂ alkyl-3-methyl-imidazolium iodide, 1-C₄ alkyl-3-methyl-imidazolium iodide, 1-C₄ alkyl-3-methyl-imidazolium hexafluorophosphate, 1-C₂ alkyl-3-methyl-imidazolium hexafluorophosphate, 1-C₃ alkyl-3-methyl-imidazolium hexafluorophosphate, 1-iso-C₃ alkyl-3-methyl-imidazolium hexafluorophosphate, 1-C₆ alkyl-3-methyl-imidazolium hexafluorophosphate, 1-C₄ alkyl-3-methyl-imidazolium tetrafluoroborate, 1-C₂ alkyl-3-methyl-imidazolium tetrafluoroborate, 1-C₂ alkyl-3-methyl-imidazolium acetate, and 1-C₂ alkyl-3-methyl-imidazolium trifluoroacetate.

The method of making the fabrics comprising the regenerated cellulose fibers and nanoparticle can include (b) recovering a solid nanoparticle-modified regenerated cellulose material comprising the cellulose substrate and the nanoparticle. Recovering the solid nanoparticle-modified regenerated cellulose material can include extruding, spinning, casting, coating, or a combination thereof. The method can also include (c) processing the solid nanoparticle-modified regenerated cellulose material to form the fabric.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate several embodiments of this disclosure and together with the description, serve to explain the principles described herein.

FIG. 1 is a schematic drawing of a bench-scale spinning line for producing regenerated cellulose fiber/film products. This spinning line includes a cellulose solution preparation system, an extruder, a spin bath, a heater, and a fiber/film winder.

FIG. 2 is a graph showing the degree of crystallinity in a regenerated bagasse fiber.

FIG. 3 is a flow chart showing the steps for preparing thermally functioning fibers including ionic liquid (IL) solution preparation, fiber fabrication, fabric knitting, fabric thermal testing, and apparel thermal modeling.

DETAILED DESCRIPTION

Provided herein are compositions, articles, and systems comprising regenerated cellulose fibers. The compositions can further include nanoparticles. Methods of making and using the compositions are also described herein.

The compositions and methods described herein can be understood more readily by reference to the following detailed description of specific aspects of the disclosed subject matter and the Examples included therein. However, before the present compositions and methods are described, it is to be understood that the aspects described below are not limited to specific synthetic methods or specific reagents, as such may, of course, vary. It is also to be understood that the terminology used herein is for the purpose of describing particular aspects only and is not intended to be limiting.

Also, throughout this specification, various publications are referenced. The disclosures of these publications in their entireties are hereby incorporated by reference into this application in order to more fully describe the state of the art to which the disclosed matter pertains. The references disclosed are also individually and specifically incorporated by reference herein for the material contained in them that is discussed in the sentence in which the reference is relied upon.

General Definitions

In this specification and in the claims that follow, reference will be made to a number of terms, which shall be defined to have the following meanings:

The term “fabric” as used herein refers to a web having a structure of individual fibers or threads which are interlaid by weaving (woven), knitting, braiding, or in an irregular, non-repetitive manner (non-woven). A nonwoven fabric or web can be formed from for example, melt-blowing processes, spun-bonding processes, and bonded carded web processes.

Throughout this specification the word “comprise” and other forms of the word, such as “comprising” and “comprises,” means including but not limited to, and is not intended to exclude, for example, other additives, components, integers, or steps. The term “include” and other forms of “include” has the same meaning as “comprise” and its other forms.

The singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to “a composition” includes mixtures of two or more such compositions, reference to “an ionic liquid” includes mixtures of two or more such ionic liquids, reference to “the compound” includes mixtures of two or more such compounds, and the like.

“Optional” or “optionally” means that the subsequently described event or circumstance can or cannot occur, and that the description includes instances where the event or circumstance occurs and instances where it does not.

Chemical Definitions

Terms used herein will have their customary meaning in the art unless specified otherwise. The organic moieties mentioned when defining variable positions within the general formulae described herein (e.g., the term “halogen”) are collective terms for the individual substituents encompassed by the organic moiety. The prefix C_(n)-C_(m) indicates in each case the possible number of carbon atoms in the group.

References in the specification and concluding claims to the molar ratio of a particular element or component in a composition denotes the molar relationship between the element or component and any other elements or components in the composition or article for which a part by weight is expressed. Thus, in a compound containing 2 moles of X and 5 moles of Y, X and Y are present at a molar ratio of 2:5, and are present in such ratio regardless of whether additional components are contained in the compound.

A weight percent (wt %) of a component, unless specifically stated to the contrary, is based on the total weight of the formulation or composition in which the component is included.

The term “ion,” as used herein, refers to any molecule, portion of a molecule, cluster of molecules, molecular complex, moiety, or atom that contains a charge (positive, negative, or both at the same time within one molecule, cluster of molecules, molecular complex, or moiety (e.g., zwitterions)) or that can be made to contain a charge. Methods for producing a charge in a molecule, portion of a molecule, cluster of molecules, molecular complex, moiety, or atom can be accomplished by methods known in the art, e.g., protonation, deprotonation, oxidation, reduction, alkylation acetylation, esterification, deesterification, hydrolysis, etc.

The term “anion” is a type of ion and is included within the meaning of the term “ion.” An “anion” is any molecule, portion of a molecule (e.g., zwitterion), cluster of molecules, molecular complex, moiety, or atom that contains a net negative charge or that can be made to contain a net negative charge. The term “anion precursor” is used herein to specifically refer to a molecule that can be converted to an anion via a chemical reaction (e.g., deprotonation).

The term “cation” is a type of ion and is included within the meaning of the term “ion.” A “cation” is any molecule, portion of a molecule (e.g., zwitterion), cluster of molecules, molecular complex, moiety, or atom, that contains a net positive charge or that can be made to contain a net positive charge. The term “cation precursor” is used herein to specifically refer to a molecule that can be converted to a cation via a chemical reaction (e.g., protonation or alkylation).

The term “alkyl,” as used herein, refers to a saturated straight, branched, primary, secondary or tertiary hydrocarbons, including those having 1 to 20 atoms. In some examples, alkyl groups will include C₁-C₁₂, C₁-C₁₀, C₁-C₈, C₁-C₆, C₁-C₅, C₁-C₄, C₁-C₃, or C₁-C₂ alkyl groups. Examples of C₁-C₁₀ alkyl groups include, but are not limited to, methyl, ethyl, propyl, 1-methylethyl, butyl, 1-methylpropyl, 2-methylpropyl, 1,1-dimethylethyl, pentyl, 1-methylbutyl, 2-methylbutyl, 3-methylbutyl, 2,2-dimethylpropyl, 1-ethylpropyl, hexyl, 1,1-dimethylpropyl, 1,2-dimethylpropyl, 1-methylpentyl, 2-methylpentyl, 3-methylpentyl, 4-methylpentyl, 1,1-dimethylbutyl, 1,2-dimethylbutyl, 1,3-dimethylbutyl, 2,2-dimethylbutyl, 2,3-dimethylbutyl, 3,3-dimethylbutyl, 1-ethylbutyl, 2-ethylbutyl, 1,1,2-trimethylpropyl, 1,2,2-trimethylpropyl, 1-ethyl-1-methylpropyl, 1-ethyl-2-methylpropyl, heptyl, octyl, 2-ethylhexyl, nonyl and decyl groups, as well as their isomers. Examples of C₁-C₄-alkyl groups include, for example, methyl, ethyl, propyl, 1-methylethyl, butyl, 1-methylpropyl, 2-methylpropyl, and 1,1-dimethylethyl groups.

Cyclic alkyl groups or “cycloalkyl” groups include cycloalkyl groups having from 3 to 10 carbon atoms. Cycloalkyl groups can include a single ring, or multiple condensed rings. In some examples, cycloalkyl groups include C₃-C₄, C₄-C₇, C₅-C₇, C₄-C₆, or C₅-C₆ cyclic alkyl groups. Non-limiting examples of cycloalkyl groups include adamantyl, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl and the like.

Alkyl and cycloalkyl groups can be unsubstituted or substituted with one or more moieties chosen from alkyl, halo, haloalkyl, hydroxyl, carboxyl, acyl, acyloxy, amino, alkyl- or dialkylamino, amido, arylamino, alkoxy, aryloxy, nitro, cyano, azido, thiol, imino, sulfonic acid, sulfate, sulfonyl, sulfanyl, sulfinyl, sulfamonyl, ester, phosphonyl, phosphinyl, phosphoryl, phosphine, thioester, thioether, acid halide, anhydride, oxime, hydrazine, carbamate, phosphoric acid, phosphate, phosphonate, or any other viable functional group that does not inhibit the biological activity of the compounds of the invention, either unprotected, or protected as necessary, as known to those skilled in the art, for example, as described in Greene, et al., Protective Groups in Organic Synthesis, John Wiley and Sons, Third Edition, 1999, hereby incorporated by reference.

Terms including the term “alkyl,” such as “alkylamino” or “dialkylamino,” will be understood to comprise an alkyl group as defined above linked to another functional group, where the group is linked to the compound through the last group listed, as understood by those of skill in the art.

The term “aryl,” as used herein, refers to a monovalent aromatic carbocyclic group of from 6 to 14 carbon atoms. Aryl groups can include a single ring or multiple condensed rings. In some examples, aryl groups include C₆-C₁₀ aryl groups. Aryl groups include, but are not limited to, phenyl, biphenyl, naphthyl, tetrahydronaphtyl, phenylcyclopropyl and indanyl. Aryl groups can be unsubstituted or substituted by one or more moieties chosen from halo, cyano, nitro, hydroxy, mercapto, amino, alkyl, alkenyl, alkynyl, cycloalkyl, cycloalkenyl, haloalkyl, haloalkenyl, haloalkynyl, halocycloalkyl, halocycloalkenyl, alkoxy, alkenyloxy, alkynyloxy, haloalkoxy, haloalkenyloxy, haloalkynyloxy, cycloalkoxy, cycloalkenyloxy, halocycloalkoxy, halocycloalkenyloxy, alkylthio, haloalkylthio, cycloalkylthio, halocycloalkylthio, alkylsulfinyl, alkenylsulfinyl, alkynyl-sulfinyl, haloalkylsulfinyl, haloalkenylsulfinyl, haloalkynylsulfinyl, alkylsulfonyl, alkenylsulfonyl, alkynylsulfonyl, haloalkyl-sulfonyl, haloalkenylsulfonyl, haloalkynylsulfonyl, alkylamino, alkenylamino, alkynylamino, di(alkyl)amino, di(alkenyl)-amino, di(alkynyl)amino, or trialkylsilyl.

The term “alkoxy,” as used herein, refers to alkyl-O—, wherein alkyl refers to an alkyl group, as defined above. Similarly, the terms “alkenyloxy,” “alkynyloxy,” and “cycloalkoxy,” refer to the groups alkenyl-O—, alkynyl-O—, and cycloalkyl-O—, respectively, wherein alkenyl, alkynyl, and cycloalkyl are as defined above. Examples of C₁-C₆-alkoxy groups include, but are not limited to, methoxy, ethoxy, C₂H₅—CH₂O—, (CH₃)₂CHO—, n-butoxy, C₂H₅—CH(CH₃)O—, (CH₃)₂CH—CH₂O—, (CH₃)₃CO—, n-pentoxy, 1 methylbutoxy, 2-methylbutoxy, 3-methylbutoxy, 1,1-dimethylpropoxy, 1,2 dimethylpropoxy, 2,2-dimethyl-propoxy, 1-ethylpropoxy, n-hexoxy, 1 methylpentoxy, 2-methylpentoxy, 3-methylpentoxy, 4-methylpentoxy, 1,1 dimethylbutoxy, 1,2-dimethylbutoxy, 1,3-dimethylbutoxy, 2,2-dimethylbutoxy, 2,3 dimethylbutoxy, 3,3-dimethylbutoxy, 1-ethylbutoxy, 2-ethylbutoxy, 1,1,2 trimethylpropoxy, 1,2,2-trimethylpropoxy, 1-ethyl-1-methylpropoxy, and 1-ethyl-2-methylpropoxy.

The term “heteroaryl,” as used herein, refers to a monovalent aromatic group of from 1 to 15 carbon atoms (e.g., from 1 to 10 carbon atoms, from 2 to 8 carbon atoms, from 3 to 6 carbon atoms, or from 4 to 6 carbon atoms) having one or more heteroatoms within the ring. The heteroaryl group can include from 1 to 4 heteroatoms, from 1 to 3 heteroatoms, or from 1 to 2 heteroatoms. In some examples, the heteroatom(s) incorporated into the ring are oxygen, nitrogen, sulfur, or combinations thereof. When present, the nitrogen and sulfur heteroatoms can optionally be oxidized. Heteroaryl groups can have a single ring (e.g., pyridyl or furyl) or multiple condensed rings provided that the point of attachment is through a heteroaryl ring atom. Preferred heteroaryls include pyridyl, piridazinyl, pyrimidinyl, pyrazinyl, triazinyl, pyrrolyl, indolyl, quinolinyl, isoquinolinyl, quinazolinyl, quinoxalinnyl, furanyl, thiophenyl, furyl, pyrrolyl, imidazolyl, oxazolyl, isoxazolyl, isothiazolyl, pyrazolyl benzofuranyl, and benzothiophenyl. Heteroaryl rings can be unsubstituted or substituted by one or more moieties as described for aryl above.

Exemplary monocyclic heterocyclic groups include, but are not limited to, pyrrolidinyl, pyrrolyl, pyrazolyl, oxetanyl, pyrazolinyl, imidazolyl, imidazolinyl, imidazolidinyl, oxazolyl, oxazolidinyl, isoxazolinyl, isoxazolyl, thiazolyl, thiadiazolyl, thiazolidinyl, isothiazolyl, isothiazolidinyl, furyl, tetrahydrofuryl, thienyl, oxadiazolyl, piperidinyl, piperazinyl, 2-oxopiperazinyl, 2-oxopiperidinyl, 2-oxopyrrolodinyl, 2-oxoazepinyl, azepinyl, 4-piperidonyl, pyridinyl, pyrazinyl, pyrimidinyl, pyridazinyl, tetrahydropyranyl, morpholinyl, thiamorpholinyl, thiamorpholinyl sulfoxide, thiamorpholinyl sulfone, 1,3-dioxolane and tetrahydro-1,1-dioxothienyl, triazolyl, triazinyl, and the like.

The term “halogen” or “halide,” as used herein, refers to the atoms fluorine, chlorine, bromine, and iodine. The prefix halo- (e.g., as illustrated by the term haloalkyl) refers to all degrees of halogen substitution, from a single substitution to a perhalo substitution (e.g., as illustrated with methyl as chloromethyl (—CH₂Cl), dichloromethyl (—CHCl₂), trichloromethyl (—CCl₃)).

The term “cyclic group” or “ring” is used herein to refer to either aryl groups, non-aryl groups (i.e., cycloalkyl, heterocycloalkyl, cycloalkenyl, and heterocycloalkenyl groups), or both. Cyclic groups have one or more ring systems that can be substituted or unsubstituted. A cyclic group or ring can contain one or more aryl groups, one or more non-aryl groups, or one or more aryl groups and one or more non-aryl groups.

The terms “amine” or “amino” as used herein are represented by the formula NR¹R²R³, where R¹, R², and R³ can be, independently, hydrogen, an alkyl, halogenated alkyl, alkenyl, alkynyl, aryl, heteroaryl, cycloalkyl, cycloalkenyl, heterocycloalkyl, or heterocycloalkenyl group described above.

The term “carboxylic acid” as used herein is represented by the formula —C(O)OH. A “carboxylate” as used herein is represented by the formula —C(O)O⁻.

As used herein, the term “substituted” is contemplated to include all permissible substituents of organic compounds. In a broad aspect, the permissible substituents include acyclic and cyclic, branched and unbranched, carbocyclic and heterocyclic, and aromatic and nonaromatic substituents of organic compounds. Illustrative substituents include, for example, those described below. The permissible substituents can be one or more and the same or different for appropriate organic compounds. For purposes of this disclosure, the heteroatoms, such as nitrogen, can have hydrogen substituents and/or any permissible substituents of organic compounds described herein which satisfy the valences of the heteroatoms. This disclosure is not intended to be limited in any manner by the permissible substituents of organic compounds. Also, the terms “substitution” or “substituted with” include the implicit proviso that such substitution is in accordance with permitted valence of the substituted atom and the substituent, and that the substitution results in a stable compound, e.g., a compound that does not spontaneously undergo transformation such as by rearrangement, cyclization, elimination, etc. Unless otherwise stated herein, if a group is identified as being “substituted” it is meant that the group is substituted with one or more alkyl, alkoxy, alkenyl, alkynyl, aryl, heteroaryl, aldehyde, amino, carboxylic acid, ester, ether, halide, hydroxy, ketone, nitro, silyl, sulfonyl, sulfone, sulfoxide, or thiol groups.

The term “ionic liquid” describes a salt with a melting point below 150° C., whose melt is composed of discrete ions.

Reference will now be made in detail to specific aspects of the disclosed materials, compounds, compositions, articles, and methods, examples of which are illustrated in the accompanying Examples.

Compositions

Provided herein are regenerated cellulose compositions. “Regenerated” as used herein refers to a material which is obtained by dissolving and regenerating a natural cellulose, which exhibits a typical Cellulose II crystalline structure with three Cellulose II peaks located at 2θ=about 11.98° (−1 1 0), about 19.84° (1 1 0), and about 21.49° (−1 2 1). The crystalline structure of the regenerated cellulose can be determined by deconvoluting the X-ray diffraction pattern of the regenerated cellulose (FIG. 2), such as determined in L. Sun et al., Carbohydrate Polymers, 2015, 118:150-155. In the analysis of the X-ray diffraction pattern, two assumptions are made: Cellulose I has unit cell dimensions of a=7.906 Å, b=8.201 Å, c=10.38 Å, α=90°, β=90°, and γ=96.5°; Cellulose II has unit cell dimensions of a=8.10 Å, b=9.03 Å, c=10.31 Å, α=90°, β=90°, and γ=117.10°.

The regenerated cellulose described herein can be derived from a biomass. The term “biomass,” as used herein, refers to living or dead biological material that can be used in one or more of the disclosed processes. Biomass can include any cellulosic or lignocellulosic material and includes materials comprising cellulose, and optionally further comprising hemicellulose, lignin, starch, oligosaccharides and/or monosaccharides, biopolymers, natural derivatives of biopolymers, their mixtures, and breakdown products (e.g., metabolites). Biomass can also comprise additional components, such as protein and/or lipid. Biomass can be derived from a single source, or biomass can comprise a mixture derived from more than one source. Examples of biomass include trees (e.g., pine), branches, roots, leaves, wood chips, wood pulp, sawdust, bamboo, shrubs and bushes, vegetables, fruits, flowers, animal manure, multi-component feed, bioenergy crops, agricultural residues, municipal solid waste, industrial solid waste, sludge from paper manufacture, yard waste, wood and forestry waste, corn grain, corn cobs, crop residues such as corn husks, corn stover, grasses, wheat, wheat straw, hay, rice straw, switchgrass, waste paper, sugar cane bagasse, sorghum, soy, or components obtained from milling of grains. In certain embodiments, the regenerated cellulose described herein can be derived from fibrous cellulose, paper, cotton (such as cotton balls or linters), wood pulp, bagasse, bast fiber, or a combination thereof.

The regenerated cellulose can be formed into compositions (e.g. fabrics) having various properties. For example, a nanoparticle can be incorporated into the regenerated cellulose fibers to confer certain desirable properties to the regenerated cellulose fibers. The term “nanoparticle” as used herein, refers to any structure with one or more nanosized features. A nanosized feature can be any feature with at least one dimension less than 1 um in size. The nanoparticle can have any of a wide variety of shapes including for example, spheroidal and elongated nanostructures. Thus, the term nanoparticle includes nanowires, nanotubes, spheroidal nanoparticles, and the like, or combinations thereof.

The nanoparticles used herein can have an average diameter of 900 nanometers (nm) or less. In some embodiments, the average diameter of the nanoparticle can be 800 nm or less, 700 nm or less, 600 nm or less, 500 nm or less, 450 nm or less, 400 nm or less, 350 nm or less, 300 nm or less, 250 nm or less, 200 nm or less, 150 nm or less, 100 nm or less, or 50 nm or less. In some embodiments, the average diameter of the nanoparticle can be 5 nm or greater, 50 nm or greater, 100 nm or greater, 150 nm or greater, 200 nm or greater, 250 nm or greater, 300 nm or greater, 350 nm or greater, 400 nm or greater, 450 nm or greater, 500 nm or greater, 600 nm or greater, 700 nm or greater, 800 nm or greater, or 900 nm or greater. The average diameter of the nanoparticle can range from any of the minimum values described above to any of the maximum values described above. For example, the average diameter of the nanoparticle can range from 5 nm to 700 nm, from 5 nm to 500 nm, from 50 nm to 500 nm, or from 50 nm to 250 nm.

The nanoparticles can be encapsulated within the regenerated cellulose fibers, dispersed throughout the regenerated cellulose material, or form a layer/coating on the regenerated cellulose fibers. The nanoparticles can attach permanently or semi-permanently to the regenerated cellulose fibers. The nanoparticles can adhere to the regenerated cellulose fibers covalently or non-covalently. In some cases, the nanoparticle is unreactive with the regenerated cellulose fibers.

As described herein, the nanoparticles can confer certain desirable properties to the regenerated cellulose fibers. In some embodiments, the nanoparticle can be selected from a thermally conductive or thermally insulating material, an electrically conductive material, an electromagnetic wave absorption or shielding material, a hydrophobic material, a fire retardant or suppressant, a water repellent material, a water absorbent material, a soil repellent material, a reflective material (such as a metallic reflector), a magnetic material, a thermochromic material, a bioactive agent (such as an anti-microbial agent, anti-fungal agent, or an insect repellent), a sunblock agent, a dye, a pigment, a fragrance, an insect repellent, a fabric softener, a UV-protective material, an oxidation resistant material, or a combination thereof. In some examples, the nanoparticle included in the regenerated cellulose fibers is a thermally conductive or thermally insulating nanoparticle. In some examples, the nanoparticle included in the regenerated cellulose fibers is a thermally conductive or thermally insulating nanoparticle.

In some embodiments, the thermal insulating material can include a far infrared radiation ceramic, a thermal conductive carbon material, or a combination thereof. Examples of thermal insulating material can include aluminum, iron, silver, cerium, zinc, gold, copper, cobalt, nickel, platinum, manganese, rhodium, ruthenium, palladium, titanium, vanadium, chromium, molybdenum, cadmium, mercury, calcium, zirconium, iridium, silicon, an oxide thereof, zeolite, graphite, carbon nanotubes, or a combination thereof. Specific examples of thermal insulating nanoparticle includes alumina, silica, titanium oxide, tin oxide, iron oxide, cesium oxide, zinc oxide, graphite, carbon nanotubes, or a combination thereof.

In some embodiments, the regenerated cellulose can include a nanoparticle selected from silicon oxide nanoparticles, silver nanoparticles, cerium oxide nanoparticles, zinc oxide nanoparticles, polyvinyl alcohol nanoparticles, and combinations thereof.

The compositions described herein can comprise 0.01% or greater by weight nanoparticle (i.e. based on the total weight of the regenerated cellulose and the nanoparticle). For example, the compositions can comprise 0.1% or greater, 0.2% or greater, 0.5% or greater, 1% or greater, 1.5% or greater, 2% or greater, 3% or greater, 4% or greater, 5% or greater, 6% or greater, 7% or greater, 8% or greater, 9% or greater, 10% or greater, 12% or greater, 15% or greater, 20% or greater, or 25% or greater by weight nanoparticle, based on the weight of the composition. In some examples, the compositions can comprise 25% or less, 20% or less, 15% or less, 12% or less, 10% or less, 9% or less, 8% or less, 7% or less, 6% or less, 5% or less, 4% or less, 3% or less, 2.5% or less, 2% or less, 1.5% or less, 1% or less, 0.5% or less by weight nanoparticle, based on the weight of the composition. The amount of nanoparticles in the composition can range from any of the minimum values described above to any of the maximum values described above. For example, the amount of nanoparticle in the composition can range from 0.01% to 25%, 0.01% to 20%, 0.01% to 15%, 0.01% to 10%, 0.01% to 5%, 0.5% to 10%, 0.5% to 5%, or 1% to 5% by weight, based on the weight of the composition.

In some embodiments, the weight ratio of the nanoparticles to regenerated cellulose in the composition can be 1:4 or less. For example, the weight ratio of the nanoparticle to regenerated cellulose in the composition can be 1:5 or less, 1:7.5 or less, 1:10 or less, 1:15 or less, 1:20 or less, 1:25 or less, 1:50 or less, 1:75 or less, or 1:100 or less. In some embodiments, the weight ratio of the nanoparticles to regenerated cellulose in the composition can be 1:100 (e.g., at least 1:75, at least 1:50, at least 1:25, at least 1:20, at least 1:15, at least 1:10, at least 1:5, or at least 1:4). The weight ratio of nanoparticle to regenerated cellulose in the composition can range from any of the minimum values described above to any of the maximum values described above. For example, the weight ratio of nanoparticles to regenerated cellulose in the composition can range from 1:100 to 1:4 (e.g., from 1:100 to 1:25, from 1:100 to 1:20, or from 1:50 to 1:20).

Methods

Methods of making the nanoparticle modified regenerated cellulose material and compositions comprising the same are also provided herein. As described herein, the nanoparticle modified regenerated cellulose material can be a fabric. The methods can include at least partially dissolving a cellulose substrate in a medium comprising one or more ionic liquids. The cellulose substrate can be a biomass as described herein. The medium can be heated or irradiated to aid in dissolution of the cellulose substrate.

The term “ionic liquid” has many definitions in the art, but is used herein to refer to salts (i.e., compositions comprising cations and anions) that are liquid at a temperature of at or below about 150° C., e.g., at or below about 120, 100, 80, 60, 40, or 25° C. That is, at one or more temperature ranges or points at or below about 150° C. the disclosed ionic liquid compositions are liquid; although, it is understood that they can be solids at other temperature ranges or points. The use of the term “liquid” to describe the disclosed ionic liquid compositions is meant to describe a generally amorphous, non-crystalline, or semi-crystalline state. For example, while some structured association and packing of cations and anions can occur at the atomic level, the disclosed ionic liquid compositions have minor amounts of such ordered structures and are therefore not crystalline solids. The compositions disclosed herein can be fluid and free-flowing liquids or amorphous solids such as glasses or waxes at a temperature at or below about 150° C. In particular examples disclosed herein, the disclosed ionic liquid compositions are liquid at which the composition is applied (i.e., ambient temperature).

The disclosed ionic liquid compositions are materials composed of one or more cations and one or more anions. The mixture of cations and anions may be selected and optimized for the dissolution of a particular cellulose substrate material. In some embodiments, the cation portion of the ionic liquid can be derived from an imidazole, a pyrazole, a thiazole, an isothiazole, an azathiozole, an oxothiazole, an oxazine, an oxazoline, an oxazaborole, a dithiozole, a triazole, a selenozole, an oxaphosphole, a pyrrole, a borole, a furan, a thiophen, a phosphole, a pentazole, an indole, an indoline, an oxazole, an isoxazole, an isotriazole, a tetrazole, a benzofuran, a dibenzofuran, a benzothiophen, a dibenzothiophen, a thiadiazole, pyridine, a pyrimidine, a pyrazine, a pyridazine, a piperazine, a piperidine, a morpholone, a pyran, an annoline, a phthalazine, a quinazoline, a quinoxaline, a quinoline, a pyrrolidine, an isoquinoline, or a combination thereof.

The one or more ionic liquids have an anionic portion which can be selected from a halogen, a pseudohalogen, BX₄ ⁻ wherein X is halogen, PF₆ ⁻, AsF₆ ⁻, SbF₆ ⁻, NO₂ ⁻, NO₃ ⁻, SO₄ ²⁻, BR₄ ⁻, phosphates, phosphites, polyoxometallates, carboxylates, substituted carboxylates, triflates, carboranes, substituted carboranes, metallocarboranes, and substituted metallocarboranes; wherein R is selected from hydrogen, alkyl, substituted alkyl, cycloalkyl, substituted cycloalkyl, heteroalkyl, hetero cycloalkyl, substituted heterocycloalkyl, aryl, substituted aryl, heteroaryl, substituted heteroaryl, alkoxy, aryloxy, acyl, silyl, boryl, phosphino, amino, thio, seleno, or a combination thereof.

In some embodiments, the one or more ionic liquids may be selected from 1-C₂ alkyl-3-methyl-imidazolium chloride, 1-C₃ alkyl-3-methyl-imidazolium chloride, 1-C₄ alkyl-3-methylimidazolium chloride, 1-C₆ alkyl-3-methyl-imidazolium chloride, 1-C₈ alkyl-3-methyl-imidazolium chloride, 1-C₂ alkyl-3-methyl-imidazolium iodide, 1-C₄ alkyl-3-methyl-imidazolium iodide, 1-C₄ alkyl-3-methyl-imidazolium hexafluorophosphate, 1-C₂ alkyl-3-methyl-imidazolium hexafluorophosphate, 1-C₃ alkyl-3-methyl-imidazolium hexafluorophosphate, 1-iso-C₃ alkyl-3-methyl-imidazolium hexafluorophosphate, 1-C₆ alkyl-3-methyl-imidazolium hexafluorophosphate, 1-C₄ alkyl-3-methyl-imidazolium tetrafluoroborate, 1-C₂ alkyl-3-methyl-imidazolium tetrafluoroborate, 1-C₂ alkyl-3-methyl-imidazolium acetate, and 1-C₂ alkyl-3-methyl-imidazolium trifluoroacetate.

The medium comprising the cellulose substrate and the ionic liquid can include the cellulose substrate in an amount of 50% or less by weight of the medium, such 35% by less, 25% by less, 10% by less, 5% by less, 3% by less, or 2% by less.

The method of preparing the nanoparticle modified regenerated cellulose material can include dissolving and/or suspending one or more nanoparticle in the medium comprising the one or more ionic liquids. The nanoparticle can be substantially uniformly distributed within the medium. The amount of nanoparticle included in the medium can be 0.001% to 5% by weight, based on the total weight of the medium (i.e. including the one or more ionic liquid). In some embodiments, the nanoparticle can be added in an amount to the medium such that the spinnability of the medium is not significantly affect but would significantly increase thermal insulation or thermal conductivity of the regenerated cellulose fiber.

The method of preparing the nanoparticle modified regenerated cellulose material can include recovering a solid nanoparticle modified regenerated cellulose material comprising the cellulose substrate and the nanoparticle. Recovering the solid nanoparticle-modified regenerated cellulose material can comprise spinning, extruding, casting, or a combination thereof. In some embodiments, the nanoparticle modified regenerated cellulose fibers can be recovered by a spinning process such as a gap/dry-wet spinning process or by a wet-wet spinning process. For example, recovering the nanoparticle modified regenerated cellulose fibers can include feeding the mixture comprising the cellulose substrate and nanoparticle into an extruder for fiber spinning with a dry-wet spinning method. The regenerated cellulose-containing mixture can be extruded into a non-solvent such as water, an alcohol, or other hydric liquids. When the regenerated cellulose-containing mixture is extruded into the non-solvent, such as a water bath, nanoparticle modified regenerated cellulose fibers can be precipitated through solution quenching and anti-solvent (water) addition into the solution system. The addition of the anti-solvent reduces the solubility of cellulose in the ionic liquid, resulting in a condition of supersaturation that is a driving force for cellulose nucleation and growth. The regenerated nanoparticle modified cellulose fiber can then be drawn, dried (for example by passing through a heater), and then wound onto a spool using a winding device. Optionally, the fibers can be ran a second-time washing and drying under the same dry setting.

In some embodiments, the nanoparticle modified cellulose mixture can be fed into a mixing extruder. The method of dry-jet and wet-spinning can be carried out with an air gap of from 20-25 mm through an orifice with a 1-2 mm diameter. The extruder rotating speed can be kept at from 170-220 rpm. The extruding temperature can be from 25-50° C. A water bath container can be used for nanoparticle modified cellulose fiber coagulation. The water bath can be kept at room temperature (about 20° C.). After coming out from the water bath, the spun fibers can pass through a glass tube for drying with hot air flow (at least 60° C.). The dried fibers can be picked up by a take-up device that can determine the drawing speeds. Table 1 lists some embodiments of control parameters for preparing regenerated nanoparticle modified cellulose fibers.

TABLE 1 Control parameters for preparing regenerated nanoparticle modified cellulose fibers. Process Parameter Control Value Dissolving/ Loading rate (wt % based on 0.01-25   dispersing cellulose and nanoparticle) nanoparticle Temperature (° C.) 30-50 Time (h) 0.5-1.0 Dissolving Concentration (wt % based on  2-12 cellulose cellulose and ionic liquid) Temperature (° C.) 20-95 Time (h) 1-3 Vacuuming pressure (psi)  1-30 Shear rate (rpm) 40-45 Fiber spinning Air gap (mm) 20-25 Orifice diameter (inch) 1/16 Rotor temperature (° C.) 40-95 Spin head temperature (° C.)  45-110 Extruding speed (rpm) 170-220 (65-85%) Extruding-winding ratio 10-30 Winding speed (mm/s)  80-225 Drying temperature (° C.) 40-60

The nanoparticle-modified regenerated cellulose fibers can be formed into a fabric. In some embodiments, the produced fibers can be converted into a fabric using a fiber analysis knitter sampler. The fabric can exhibit thermal control at various basis weight, depending on the end use of the fabric (such as the type of apparel that will be produced). The basis weight of the fabric can be 20 g/m² or greater. For example, the basis weight of the fabric can be 25 g/m² or greater, 30 g/m² or greater, 35 g/m² or greater, 40 g/m² or greater, 45 g/m² or greater, 50 g/m² or greater, 55 g/m² or greater, 60 g/m² or greater, 65 g/m² or greater, 70 g/m² or greater, 80 g/m² or greater, 90 g/m² or greater, 100 g/m² or greater, 110 g/m² or greater, 120 g/m² or greater, 130 g/m² or greater, 140 g/m² or greater, 150 g/m² or greater, 160 g/m² or greater, 170 g/m² or greater, 180 g/m² or greater, or 190 g/m² or greater. In some examples, the basis weight of the fabric can be 200 g/m² or less. For example, the basis weight of the fabric can be 190 g/m² or less, 180 g/m² or less, 170 g/m² or less, 160 g/m²or less, 150 g/m²or less, 140 g/m²or less, 130 g/m²or less, 120 g/m² or less, 110 g/m² or less, 100 g/m² or less, 90 g/m² or less, 80 g/m² or less, 70 g/m² or less, 65 g/m² or less, 60 g/m² or less, 55 g/m² or less, or 50 g/m² or less. The basis weight of the fabric can range from any of the minimum values described above to any of the maximum values described above. For example, the basis weight of the fabric can range from 25 g/m² to 200 g/m², from 50 g/m² to 200 g/m², from 50 g/m² to 190 g/m², or from 50 g/m² to 150 g/m². The fabrics described herein can range from heavy to light.

The fabrics can be made into textiles including jackets, coats, skirts, pants, suits, slacks, vests, gloves, and the like. The fabrics can also be used in non-apparel applications such as furniture and carpets.

As described above, the nanoparticle incorporated into the regenerated cellulose fibers can provide various properties to the fabric, and ultimately to the apparel it is used to make. In some examples, the properties associated with the nanoparticles incorporated into the fabric include aesthetics (e.g., luminescence), shrink resistance, anti-microbial, stain resistance, electrical conductivity, thermal conductivity, thermal insulation, static protection, fire resistance, UV protection, fragrance release, water repellent (hydrophobic), high strength, wrinkle resistance, moisture management, and/or self-cleaning properties. As an example, silver nanoparticles can inhibit bacterial metabolism, which causes infection and odor, causing the bacteria to die. Rare earth metals can fluoresce to detect infrared in textile electroluminescent tagging systems. Carbon nanotubes provide very high strength properties due to graphitic structure. Carbon nanotubes can reinforce the polymer matrix of the cellulose fiber. Titanium dioxide can be applied to textiles that are changed from hydrophobic (water repelling) to hydrophilic (water attracting) by light. Lightweight silica aerogel has high thermal insulating properties that can be used in insulating textiles. Conductive zinc oxide nanoparticles can disperse static charge developed on textile fibers.

In some embodiments, the regenerated nanoparticle modified cellulose fibers can exhibit improved fiber fineness and tensile strength, compared to the fibers that does not include the nanoparticles described herein. The fineness of the fiber can be determined by fiber linear density in Denier (1 denier=1 gram per 9000 m). The procedure to measure the fiber linear density complies with ASTM D 1577. An Instron tensile tester can be used for measuring the fiber and film tensile strength and break elongation. The test method for tensile strength (tenacity in g/denier) is in accordance with the standard method ASTM D 3822 for single textile fiber break strength.

In some embodiments, the regenerated nanoparticle modified cellulose fibers or fabrics produced therefrom can exhibit improved thermal insulation. For example, the regenerated nanoparticle modified cellulose fibers can exhibit an increase in the total thermal resistance of up to 1.17 times that of current non-thermal regulating winter suits. Exemplary non-thermal winter suits include suits made up of 100% wool fabric (or wool-rich fabric including 50% or greater wool such as 50/50 wool/polyester) as a surface and 100% rayon fabric as a lining. The non-thermal winter suit (including top and pant) can have a weight of about 2 lbs. In some embodiments, the regenerated nanoparticle modified cellulose fibers can exhibit a reduction in the total thermal resistance to 0.78 times that of current non-thermal regulating summer suits. The thermal properties of the nanoparticle modified cellulose fibers and films can be characterized. In particular, the thermal stability can be measured from 30 to 600° C. at a heating rate of 5° C./min by a Shimadzu TGA-50 thermogravimetric analyzer.

The thermal properties of materials can be characterized by a number of characteristics, such as thermal conductivity, thermal diffusivity and thermal effusivity. Thermal conductivity is a measure of the ability of material to conduct heat (W/mK). Thermal diffusivity measures the ability of a material to conduct thermal energy relative to its ability to store energy (mm2/s) Thermal effusivity is defined as the square root of the product of thermal conductivity (k), density (p) and heat capacity (cp) of a material (Ws^(1/2)/m²K).

In some embodiments, the regenerated nanoparticle modified cellulose fibers or fabrics produced therefrom can exhibit improved thermal conductivity. For example, the regenerated nanoparticle modified cellulose fibers can exhibit an increase in the total thermal conductivity of up to two times or greater that of cellulose. In some embodiments, the regenerated nanoparticle modified cellulose fibers can exhibit a conductivity of greater than 0.04 W/mK (e.g., 0.05 W/mK or greater, 0.06 W/mK or greater, or 0.07 W/mK or greater, or from 0.05 to 0.1 W/mK, or from 0.05 to 0.08 W/mK).

In some embodiments, the regenerated nanoparticle modified cellulose fibers or fabrics produced therefrom can exhibit improved effusivity. For example, the regenerated nanoparticle modified cellulose fibers can exhibit an increase in the effusivity of up to three times or greater than that of cellulose. In some embodiments, the regenerated nanoparticle modified cellulose fibers can exhibit an effusivity of greater than 100 W s^(1/2) m⁻² K⁻¹ (e.g., 120 W s^(1/2) m⁻² K⁻¹ or greater, 130 W s^(1/2) m⁻² K⁻¹ or greater, 140 W s^(1/2) m⁻² K⁻¹ or greater, 150 W s^(1/2) m⁻² K⁻¹ or greater, 160 W s^(1/2) m⁻² K⁻¹ or greater, 170 W s^(1/2) m⁻² K⁻¹ or greater, from 130 to 200 W s^(1/2) m⁻² K⁻¹, or from 150 to 180 W s^(1/2) m⁻² K⁻¹).

The nanoparticle interface and dispersion in the cellulose matrix can be analyzed using a FEI Quanta FEG 650 environmental scanning electron microscope (SEM) equipped with an energy dispersive spectroscopy and a field emission SEM with a capacity of scanning-transmission electron microscopy (STEM) imaging. The nanoparticle distribution and cluster size can be analyzed using an image analysis mode. The morphological structure of the regenerated cellulose can be evaluated using an instrument of transmission electron microscopy, JEOL 2010F HRTEM.

EXAMPLES Background: Rayon Fiber Use and Production

There are two physical attributes to apparel comfort: heat transport (including conduction, air flow convection, and radiation) and moisture transport (including absorption, evaporation, diffusion, and wicking). These physical properties are primarily determined by fiber thermal and hygral properties and textile structures (Hearle, 1994). It is known that textile fiber as the smallest unit to form apparels plays an important role in temperature regulation inside an apparel system.

Rayon fiber is the first man-made fiber entering into textile and apparel uses over 120 years ago. However, it remains one of the favorite apparel fibers because of its silky luster, soft hand, elegant drapability, and excellent water absorbency. Current world production capacity of the cellulosic manufactured fibers is about 6,600 million pounds (3.0 million metric tons) per annum, of which 97% is rayon fiber; 2% is acetate fiber; and 1% is lyocell (Tencel®) fiber. This production capacity accounts for approximately 5% of the world man-made fiber production. It shows that global rayon production and demand keeps growing at an increasing rate of 3.8% per year from 2009 to 2014 (Blagoev, Bizzari, & Inoguchi, 2011).

However, rayon fiber manufacturers use large quantities of strong acid and alkaline chemicals that cause harsh working conditions and severe pollution. For this reason, rayon manufacturing facilities no longer exist inside the U.S. Lyocell fiber is a new generation of regenerated cellulose fiber produced from an environmentally-friendly cellulose process with no chemical reactions or effluents. Lyocell fiber is manufactured by directly dissolving cellulose into the solvent N-methylmorpholine-n-oxide (NMMO) and extruding the cellulose solution into a water bath for fiber formation. However, current production capacity of Lyocell fiber is too limited to compete with the well-established manufacture of viscose rayon fiber, and consumers pay higher prices for Lyocell-related textile and apparel products.

The example below exemplifies the fabrication of thermally functioning rayon fibers and evaluation of the thermal regulating efficiency of the new rayon fibers as used in a 3-layer suiting garment structure.

Nanoparticle Dispersion

Table 2, below lists three far infrared (FIR) ceramic nanoparticles (ZrO₂, Fe₂O₃, and Al₂O₃) and two carbon nanoparticles, carbon nanotube (CNT) and nanographite (C), that were selected for producing cellulose/nanoparticle composite solutions using [EMIM]Ac purchased from Sigma-Aldrich Corp. To evaluate the dispersibility of the nanoparticles in [EMIM]Ac, the nanoparticles are tested by a tensiometer Sigma 701 (Biolin Scientific Inc.) to determine their wettability defined by the Washburn theory as expressed below:

${M^{2} = {\frac{C\; \rho^{2}{\gamma \cdot \cos}\; \theta}{\eta} \cdot T}},$

where M is mass of liquid absorbed on solid (g); T is time of solid-liquid contact (s); C is solid material constant characteristic; η is liquid viscosity; ρ is liquid density; γ is liquid surface tension; and θ is contact angle. This equation indicates that the mass wettability is reversely proportional to the contact angle θ.

If the wettability of the nanoparticles are high, these nanoparticles were directly dispersed in a small amount of [EMIM]Ac vibrated by an ultrasonic device (VWR Model 50T) for 1 h. For the nanoparticles with low wettability, they were added into a small amount of N,N-dimethylformamide (DMF) for a homogeneous dispersion using an ultrasonic device. The DMF suspension was added into [EMIM]Ac, mixed for 0.5 h to remove DMF under heating and vacuuming, before adding the cellulose powder.

TABLE 2 Thermal insulation and conductive nanoparticles used for fiber spinning Density Thermal Conductivity Specific Heat Nanoparticle (g/cm³) (W/m · K) (J/kg · K) Specification ZrO₂ 5.68 1.7-2.7  420-540 purity 99.95%, APS 29-68 nm^(ii) Fe₂O₃ 5.24 6.4  651^(i) Purity 98%, APS 20-50 nm Al₂O₃ 3.95-4.10 30 901 Purity 99%, APS 40-80 nm CNT 1.30-1.40 3500 625 Purity 95%, OD 3-20 nm, length 0.1-10 μm C 2.26 300-1500 710 purity 99.66%, APS 100-500 nm^(iii)

Cellulose Dissolution and Fiber Spinning

The dispersed nanoparticle and ground cellulose power from wood pulp (provided by Rayonier Inc.) were added into [EMIM]Ac in a planetary mixer to prepare cellulose solutions. The cellulose dissolution was processed with controlled temperature, time, shear rate, and vacuum pressure as shown in Table 3 below.

The prepared pure cellulose and cellulose/nanoparticle solutions were fed into a lab-scale extruder (LE-075, CSI Inc.) respectively for fiber spinning with a dry-wet spinning method. When the cellulose solution was extruded into the water bath (no chemical added), cellulose fiber was precipitated through solution quenching and anti-solvent (water) addition into the solution system. The addition of the anti-solvent reduces the solubility of cellulose in [EMIM]Ac, resulting in a condition of supersaturation that is a driving force for cellulose nucleation and growth. The regenerated pure cellulose and cellulose/nanosilver fiber is drawn, dried when passing through a heater, and finally wound onto a spool using a winding device. The experimental fiber ran a second-time washing and drying under the same dry setting.

TABLE 3 Fiber fabrication parameters for processing control Process Parameter Control Value Nanoparticle Max. loading rate (% of cellulose) TBD dispersing Water bath temperature (° C.) 30-50 Time (h) 0.5-1.0 Cellulose Concentration (%) 6 dissolving Temperature (° C.) 45 Time (h) 3 Vacuuming pressure (psi) −30 Shear rate (rpm) 40 Fiber spinning Air gap (mm) 20-25 Orifice diameter (inch.) 1/16 Rotor temperature (° C.) 40 Spin head temperature (° C.) 45 Extruding speed (rpm) 170-220 (65-85%) Extruding-winding ratio 10-30 Winding speed (mm/s)  80-225 Drying temperature (° C.) 60

Measurement of Fiber Fineness, Tensile Strength, and Thermal Stability

Fineness of the experimental fiber can be determined by fiber linear density in Denier (1 denier=1 gram per 9000 m). The procedure to measure the fiber linear density complies with ASTM D 1577.

An Instron tensile tester can be used for measuring the fiber and film tensile strength and break elongation. The test method for tensile strength (tenacity in g/denier) is in accordance with the standard method ASTM D 3822 for single textile fiber break strength.

Thermal properties of the nanoparticle/cellulose fibers and films can be characterized. The thermal stability can be measured from 30 to 600° C. at a heating rate of 5° C./min by a thermogravimetry analyzer Shimazu TGA-50.

Experimental Analysis of Cellulose Crystallization

A WAXD instrument Rigaku Model RAPID II can be used for measuring the cellulose crystalline structure. After obtaining intensity curves of the Bragg reflection, a mathematical model can be used for curve fitting (Gallagher, 2002), in order to calculate the degree of crystallinity that is described by the crystallinity index (CI), a ratio between sum of area under each crystalline peak and area under total diffraction curve (Fink, Weigel, & Purz, 2001). The cellulose crystallite orientation along fiber axis can be determined by Herman's crystal orientation factor. The crystallite size L can be calculated by the Scherrer equation (Guerin & Alvarez, 1995).

Evaluation of Fiber Morphological Structure and Nanosilver Dispersibility

Examination of the silver nanoparticle interface and dispersion in the cellulose matrix was carried out using an FEI Quanta FEG 650 environmental scanning electron microscope (SEM) equipped with an energy dispersive spectroscopy (EDS of Bruker XFlash® Detector 5010), and a Hitachi S-5500 field emission SEM with a capacity of scanning-transmission electron microscopy (STEM) imaging. Silver nanoparticle distribution and cluster size were analyzed using an image analysis mode provided by the software MATLAB. The morphological structure of the regenerated cellulose was evaluated using an instrument of transmission electron microscopy, JEOL 2010F HRTEM.

Fabrication of Test Samples

The produced thermal fibers were converted into test samples using a fiber analysis knitter sampler (LH-122, Lawson-Hemphill). For a need of comparison and thermal modeling, two control fabrics were also produced, one knitted with a pure wool yarn (60s) and the other knitted with a pure cotton yarn (60s). Information of the fabric test samples is listed in Table 4.

TABLE 4 Fabric test sample specifications and estimated quantity Sample Weight Specimen No ID Fiber Type (g/m²) Size (mm) Specimen PCR pure cellulose 50 127 × 127 50 CZ cellulose/ZrO₂ 60 127 × 127 50 CF cellulose/Fe₂O₃ 60 127 × 127 50 CA cellulose/Al₂O₃ 60 127 × 127 50 CNT cellulose/CNT 60 127 × 127 50 CC cellulose/C 60 127 × 127 50 PW 60s pure wool yarn 100 127 × 127 40 PC 60s pure wool yarn 80 127 × 127 40

Model Construction of Suiting Garment System

A commonly-used suiting garment system consists of a suit and shirt for men (or a blazer and blouse for women). The suiting garment can be a 3-layer apparel structure with Inner Layer (1) (shirting fabric), In-Between Layer (2) (suit lining fabric), and Outer Layer (3) (suiting fabric). While shirts are considered wearable all year round, suits are categorized as winter suits and summer suits mainly dependent on fabric thickness and weight. In order to determine the capacity of thermal insulation or thermal transmittance for a typical suiting garment system (non-LTMS), and to examine how to constitute an LTMS suiting garment system using the developed thermal functioning fibers, three models of suiting garment system are established. Each model addresses the need for both winter and summer thermal regulation. After the model testing and calculation, it can be determined that how much of the thermal functional fiber is needed to increase the thermal resistance to 1.17 times that of the non-LTMS system for winter use, and to decrease the thermal resistance to 0.78 times that of the non-LTMS system for summer use. This will provide a practical solution for future development of a commercial LTMS suiting garment system.

Determination of Total Thermal Resistance of the Suiting Garment System

Considering the fact that dramatic sweating is not a case for suit wearers working in indoor office environment with A/C control, and that fiber thermal radiation in heat transfer becomes insignificant because the fiber volume in today's shirting and suiting fabrics is usually higher due to use of finer fiber, evaluation of total thermal resistance of the suiting garment set is based on a dry heat transfer occurring in the suiting garment fabrics dominated by conduction and surface convection only.

According to the Fourier law, heat flux density q=(W/m²) at a point in the suiting fabric layers can be expressed as:

{right arrow over (q)}=λ{right arrow over (∇)}T

where λ, is fabric thermal conductivity (W/mK) and {right arrow over (∇)}Tis temperature gradient (∂T/∂x, ∂T/∂y, ∂T/∂z). In the application of heat transfer within a garment system, the temperature gradient is often considered one-dimensional, with a direction perpendicular to body surface. To the circumstance, Eq. (2) can be simplified as:

$q_{x} = {{- \lambda}\frac{dT}{dx}}$

When the fabric thermal conductivity λ is known, thermal resistance R (m²K/W) of each of fabric layer in the suiting garment system can be calculated by R=x/λ, where x is fabric thickness (m). The heat transfer by air convection from the outer layer surface of the suit set can be described by the Newton law:

q=α·ΔT

where α is heat transfer coefficient (W/m²K) and ΔT is temperature difference. The heat transfer coefficient is related to air velocity v (m/s). In the apparel application, α can be determined by α=8.3v^(0.5). From this, the thermal resistance of the suit surface boundary layer can be obtained by this simple equation Rc=1/α. Therefore, the total thermal resistance of the suiting garment system is determined by:

$R_{sgs} = {{\sum\limits_{i = 1}^{n}R_{i}} + R_{c}}$

where n is number of fabric layer, here n=3.

Instrumental method to determine the fabric thermal resistance for each single fabric layer and for the stacked multiple layers of the suit garment system will be carried out in accordance with ASTM C_(518,) Standard Test Method for Steady-State Thermal Transmission Properties by Means of the Heat Flow Meter Apparatus. Fabric thermal effusivity can be measured by using the method described in the standard ASTM D7984 Test Method for Measurement of Thermal Effusivity of Fabrics Using a Modified Transient Plane Source (MTPS) Instrument. Fabric water vapor permeability can be tested using cup method described in ASTM E96. The test of fabric air permeability is complied with the method of ASTM D 737 for measurement of the air permeability of textile fabrics.

Conductivity and Effusivity of regenerated fibers: the conductivity and effusivity of prepared cellulose fibers as described in Table 5 were determined. The results are summarized in Table 5.

TABLE 5 Thermal properties of some experimental functional regenerated cellulose fiber. Fiber Conductivity (W m⁻¹ K⁻¹) Effusivity (W s^(1/) ² m⁻² K⁻¹) Sample A¹ 0.038 73 Sample B² 0.060 156 Sample C³ 0.064 173 ¹Pure cellulose ²Cellulose/nanosilver, A_(g) loading 0.5% ³Cellulose/MCNT-OH, MCNT-OH loading 2%

It will be apparent to those skilled in the art that various modifications and variations can be made in the present disclosure without departing from the scope or spirit of the invention. Other embodiments of the disclosure will be apparent to those skilled in the art from consideration of the specification and practice of the methods disclosed herein. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the invention being indicated by the following claims. 

1. A fabric comprising regenerated cellulose fibers and a nanoparticle dispersed throughout the fabric.
 2. The fabric of claim 1, wherein the regenerated cellulose fibers are derived from fibrous cellulose, wood pulp, cotton, paper, bast fiber, or bagasse.
 3. The fabric of claim 1, wherein the nanoparticle is unreactive with the regenerated cellulose fibers.
 4. The fabric of claim 1, wherein the nanoparticle is selected from a thermally conductive or insulating material, an electrically conductive material, an electromagnetic wave absorption or shielding material, a hydrophobic material, a fire retardant or suppressant, a water repellent material, a water absorbent material, a soil repellent material, a reflective material, an anti-microbial agent, a sunblock agent, a dye, a pigment, a fragrance, an insect repellent, a fabric softener, a UV-protective material, an oxidation resistant material, or a combination thereof.
 5. The fabric of claim 4, wherein the nanoparticle is a thermal insulating material.
 6. The fabric of claim 1, wherein the nanoparticle includes a far infrared radiation ceramic.
 7. The fabric of claim 1, wherein the nanoparticle includes aluminum, iron, silver, cerium, zinc, gold, copper, cobalt, nickel, platinum, manganese, rhodium, ruthenium, palladium, titanium, vanadium, chromium, molybdenum, cadmium, mercury, calcium, zirconium, iridium, silicon, an oxide thereof, zeolite, graphite, a carbon nanotube, or a combination thereof.
 8. The fabric of claim 1, wherein the nanoparticle is present in an amount of from 0.01% to 10% by weight, based on the total weight of the fabric.
 9. A fabric comprising regenerated cellulose fibers and a nanoparticle, wherein the fabric is prepared by a process comprising: a. providing a composition of a cellulose substrate dissolved in an ionic liquid solvent and the nanoparticle dissolved or dispersed substantially homogeneously therein; b. recovering a solid nanoparticle-modified regenerated cellulose material comprising the cellulose substrate and the nanoparticle; and c. processing the solid nanoparticle-modified regenerated cellulose material to form the fabric.
 10. The fabric of claim 9, wherein the nanoparticle includes a thermal insulating nanoparticle.
 11. The fabric of claim 10, wherein the thermal insulating nanoparticle includes a far infrared radiation ceramic, a thermal conductive carbon material, or a combination thereof.
 12. The fabric of claim 10, wherein the thermal insulating nanoparticle includes alumina, silica, titanium oxide, tin oxide, iron oxide, cesium oxide, zinc oxide, graphite, a carbon nanotube, or a combination thereof.
 13. A method of making a nanoparticle modified regenerated cellulose fabric comprising: a. providing a composition of a cellulose substrate dissolved in an ionic liquid solvent and a nanoparticle dissolved or dispersed substantially homogeneously therein; b. recovering a solid nanoparticle modified regenerated cellulose material comprising the cellulose substrate and the nanoparticle; c. processing the nanoparticle-modified regenerated cellulose material to form a fabric.
 14. The method of claim 13, wherein the providing step comprises at least partially dissolving a cellulose substrate in a medium comprising one or more ionic liquids; and dissolving or suspending a nanoparticle in the medium.
 15. The method of claim 13, wherein the cellulose substrate is derived from fibrous cellulose, wood pulp, cotton, paper, bast fiber, or bagasse.
 16. The method of claim 13, wherein the one or more ionic liquids have a cation portion derived from an imidazole, a pyrazole, a thiazole, an isothiazole, an azathiozole, an oxothiazole, an oxazine, an oxazoline, an oxazaborole, a dithiozole, a triazole, a selenozole, an oxaphosphole, a pyrrole, a borole, a furan, a thiophen, a phosphole, a pentazole, an indole, an indoline, an oxazole, an isoxazole, an isotriazole, a tetrazole, a benzofuran, a dibenzofuran, a benzothiophen, a dibenzothiophen, a thiadiazole, pyridine, a pyrimidine, a pyrazine, a pyridazine, a piperazine, a piperidine, a morpholone, a pyran, an annoline, a phthalazine, a quinazoline, a quinoxaline, a quinoline, a pyrrolidine, an isoquinoline, or a combination thereof.
 17. The method of claim 13, wherein the one or more ionic liquids have an anionic portion selected from a halogen, a pseudohalogen, BX₄ ⁻ wherein X is halogen, PF₆ ⁻, AsF₆ ⁻, SbF₆ ⁻, NO₂ ⁻, NO₃ ⁻, SO₄ ²⁻, BR₄ ⁻, phosphates, phosphites, polyoxometallates, carboxylates, substituted carboxylates, triflates, carboranes, substituted carboranes, metallocarboranes, and substituted metallocarboranes; wherein R is selected from hydrogen, alkyl, substituted alkyl, cycloalkyl, substituted cycloalkyl, heteroalkyl, hetero cycloalkyl, substituted heterocycloalkyl, aryl, substituted aryl, heteroaryl, substituted heteroaryl, alkoxy, aryloxy, acyl, silyl, boryl, phosphino, amino, thio, seleno, or a combination thereof.
 18. The method of claim 13, wherein the one or more ionic liquids are selected from 1-C₂ alkyl-3-methyl-imidazolium chloride, 1-C₃ alkyl-3-methyl-imidazolium chloride, 1-C₄ alkyl-3-methylimidazolium chloride, 1-C₆ alkyl-3-methyl-imidazolium chloride, 1-C₈ alkyl-3-methyl-imidazolium chloride, 1-C₂ alkyl-3-methyl-imidazolium iodide, 1-C₄ alkyl-3-methyl-imidazolium iodide, 1-C₄ alkyl-3-methyl-imidazolium hexafluorophosphate, 1-C₂ alkyl-3-methyl-imidazolium hexafluorophosphate, 1-C₃ alkyl-3-methyl-imidazolium hexafluorophosphate, 1-iso-C₃ alkyl-3-methyl-imidazolium hexafluorophosphate, 1-C₆ alkyl-3-methyl-imidazolium hexafluorophosphate, 1-C₄ alkyl-3-methyl-imidazolium tetrafluoroborate, 1-C₂ alkyl-3-methyl-imidazolium tetrafluoroborate, 1-C₂ alkyl-3-methyl-imidazolium acetate, and 1-C₂ alkyl-3-methyl-imidazolium trifluoroacetate.
 19. The method of claim 13, wherein recovering the solid nanoparticle-modified regenerated cellulose material comprises spinning, extruding, casting, coating, or a combination thereof. 